Research

This summary report presents an overview of the level of traveler usage (e.g., how many vehicles use the freeways) and travel performance (e.g., how fast they are traveling, where and how often congestion occurs) on the principal urban freeways in the central Puget Sound area. The freeways studied in this project are managed by the Washington State Department of Transportation (WSDOT) using its FLOW system, a coordinated network of traffic monitoring, measuring, information dissemination, and control devices that operates on urban state and Interstate highways in the central Puget Sound region. Data presented in this report were collected by the WSDOT’s freeway surveillance system.

The project that led to this report is intended to meet two separate purposes: 1) to enhance WSDOT’s ability to monitor and improve its traffic management efforts on Seattle-area highways, and 2) to provide useful information to the public and decision makers about the status of the freeway system’s operational performance. This report is primarily intended to meet the second of these objectives. However, the software developed to assist in freeway data analysis for this project and many of the graphics presented in this report are directly applicable to the first objective.